of the Fishery Board for Scotland. 21 



below 1°C. It would seem in this case as if development was practically 

 stopped at this temperature. There were lots of crystals in both live and 

 dead eggs. Some of the eggs on Plate 6 looked very well. The zona was 

 well distended. In the furthest advanced larva of Plate 11 no pulsation of 

 the heart was detected. 



At 52 days the eggs of Plate 11 all appeared to be dead. Some had died 

 at the stage of the closure of the blastopore, although some had apparently 

 died in the disc stage. I saw no embryo with pigmented eyes. The crystals 

 were numerous inside the eggs. The eggs which were arranged singly, or in 

 little groups of two or five, separate from other eggs, had died early. The 

 eggs which had developed furthest were those that were shielded by other 

 eggs. This seems to indicate that cold had been the cause of death. I did 

 not see a live egg. 



63 days. — Plates 6 and 10 had no live egg. What embryos were 

 visible were in the stages (a) in which the blastopore has just closed, and 

 (6) where the tail of the embryo reaches nearly to the head. None seemed 

 to have passed the latter stage. Where the eggs are in a single layer there are 

 many empty shells ; where they are two or more layers thick, dead embryos 

 are still present in the inside layers. Plate 6 had comparatively few eggs. 



No fry hatched from Plates 6, 10, 11. 



Plates 7 and 8. 



On February 28, Plates 7 and 8 were put on the outside of a cubical 

 wooden fi*ame which was floating in tank No. 2. The frame was quite free 

 to move about. 



Eleven days after fertilization the eggs of one of the plates were in good 

 condition, in the stage where the tail of embryo nearly reached the head. 

 The embryo moved ; the heart was beating. I could see no crystals in the 

 eggs. Some of the eggs were dead, but they did not appear to be numerous. 

 On the 25tli day some fry were observed in tank No. 2. 



26 days. — The most of the eggs were dead and covered w^ith fungus. 

 Some eggs had hatched out, and a few live eggs were ready to hatch. 

 Most of the eggs seemed to have died after the blastopore had closed. 



Plate 9. 



This plate carried ova which were not perfectly ripe. The spawn ran out 

 on pressure, but it was not perfectly translucent. The majority did not 

 swell up, and did not stick well to the plate. On February 28 it was put 

 into a metal box supplied with running unfiltered water. At that date only 

 a few eggs remained attached. They were in good condition. One or two 

 dead eggs were present. On the 25th day the plate was found to be covered 

 with a thick layer of mud. Most of its small quantity of eggs was alive. 

 The embryos were advanced ; some were ready to hatch. None had appa- 

 rently so far hatched. Some of the eggs had died after the embryo was 

 formed. I made out one crystal attached to the zona. 



Third Lot of Spawn. 



Plates 12 to 20 were coated with spawn on the morning of February 26 

 by Mr. T. Smith, St. Monans. Live herrings were principally used, but the 

 spawn was taken also from one dead fish. The plates were thickly covered 

 all over with the ova, which in some parts were several layers deep. They 

 were despatched to Aberdeen in a herring barrel, arriving there the same 

 evening. The frame carrying the plates was put into tank No. 2. 



Plates 12, 13, 16, 18, 20 were kept in uncooled water, while plates 14, 15, 

 17, 19 were put into cooled water. 



